Heretofore, the surface of a sputtering target has been finished by machining, such as, cutting, grinding, or polishing.
Due to the characteristics of machining by forcedly processing while physically breaking metal crystal grains, a large number of strains and defects, known as a surface-deformed layer, remain on the surface of the target.
Since sputtering is a process for releasing metal atoms constituting the target by using collision energy generated by physically colliding cations, such as Ar+, to a target installed on a cathode, the ease of releasing the metal atoms themselves differs depending upon the arrangement of metal atoms in a crystal (crystal orientation).
In a sputtering target having machining-affected layers as described above still remaining on the surface of the sputtering target, a stable surface state which provides a stable film deposition rate is obtained only after the target has been used for a certain period of time.
Therefore, as long as surface-deformed layers remain on the sputtering target, the deposition rate cannot be stabilized. This in turn causes an increase in the use of integrated input electric energy which is required for pre-sputtering of the target.
In order to solve such problems, a method for removing surface-deformed layers by etching the target surface has been proposed (Japanese Patent Laid-Open No. 7-118842).
However, such a method has a problem in that the integrated input energy required for pre-sputtering cannot be significantly decreased by rigorous etching under conditions suitable for removing surface-deformed layers.